JP2976992B2 - Method for producing strip-shaped Zircaloy 4 - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a zirconium-based material, and more particularly, to a method for improving the corrosion resistance of strip-shaped zircaloy 4 (which is different from the corrosion resistance of other alloys or tubular zircaloy 4).

In the development of a nuclear reactor, for example, a pressurized water reactor or a boiling water reactor, from the viewpoint of fuel design, all of the core strips and cladding tubes (strips are used to form grids, guide tubes, etc.) The demand has increased significantly. The corrosion behavior of the strip is somewhat different from the cladding. The two are significantly different in structure (i.e., the strip is rolled and the cladding is formed by the Pilger tube process). Such components are conventionally made of a zirconium-based alloy, Zircaloy 2 and Zircaloy 4. Increasing demands for such components have taken the form of longer residence times and thinner structural components, both of which involve potential corrosion and / or hydrogenation. Is causing the problem.

[0002] Commercial reactors generally use either Zircaloy 2 or Zircaloy 4 (see US Pat. Nos. 2,772,964 and 3,148,387).
No. 055). Zircaloy 2 is about 1.2
-1.7% by weight of tin (hereinafter all percentages are by weight), 0.07-0.20% of iron, approx.
Zirconium alloy containing 0.5-0.15% chromium and about 0.03-0.08% nickel. Zircaloy 4 contains about 1.2-1.7% tin, about 0.18-0.2
It contains 4% iron and about 0.07-0.13% chromium.

The manufacturing process of Zircaloy 4 has been developed with a focus on corrosion resistance. Generally, if the processing method is different,
Uniform corrosion (uniform where corrosion progresses uniformly over the entire corroded surface)
Either corrosion or nodular corrosion occurs, but not both. The effect of heat treatment variations was described by a cumulative A-parameter (see Steinberg et al.
irconium in the Nuclear I
ndustry: Sixth International
nal Symposium, ASTM STP 82
4. American Society for Te
sting and Materials, Phil
adelphia, 1984). Charquet et al. Studied the effects of early stage tube processing methods on general corrosion (400 ° C.) and heterogeneous corrosion (500 ° C.) (see D. Charquet et al.
fluence of Variations in
Early Fabrication Steps o
n Corrosion, Mechanical P
rightsies and Structures
of Zircaloy-4 Products "Z
irconium in theNuclear In
dusty: Seventh International
onal Symposium, ASTM, STP 9
39, ASTM, 1987, pp. 431-447). The results of the study by Charquet et al. Show that as the cumulative A-parameter increases, heterogeneous corrosion increases but overall corrosion decreases. Charqu
As also shown on page 441 of the et al. article, et al., the A parameter represents the normalized annealing time as known in the art and is defined by: A = t x exp (−Q / RT) where: t = annealing time (in hours); Q = activation energy of the process (calories / mol); R = general gas constant (calories / mol-degree); T = absolute temperature (in ゜). K) Cumulative A parameter indicates the α-heat treatment history of the quenched tube.

[0004] The present invention relates to an improved method for producing strip-shaped Zircaloy 4.

[0005] The gist of the present invention is to perform vacuum melting, forging, hot deformation, β-annealing, quenching, hot rolling and annealing after hot rolling of Zircaloy 4 material, and then to final dimensions. Deformation by at least two cold rolling steps including final cold rolling, wherein an intermediate annealing is performed between the cold rolling steps and a final annealing is performed after the final cold rolling step is performed. In the manufacturing method 4, the maximum working temperature between the quenching step and the final cold rolling step to the final size is set to 620 ° C., and the stress relief annealing is performed at the maximum intermediate annealing temperature of 520 ° C. Hot rolling, annealing after hot rolling, intermediate annealing time and temperature in combination to give an A parameter between 4 × 10 ^{-19 and} 7 × 10 ^-18 hours, Cold rolling process and each annealing process And the segment parameter is calculated as the execution time of the process in time, exp (-
40000 / T).
In the above, T is the absolute temperature at the time of performing the above step, and the A parameter is the sum of the segment parameters.

The gist of the present invention is to perform vacuum melting, forging, hot deformation, β-annealing, quenching, hot rolling and annealing after hot rolling of Zircaloy 4 material, and then to final dimensions. Deformation by at least two cold rolling steps including final cold rolling, wherein an intermediate annealing is performed between the cold rolling steps and a final annealing is performed after the final cold rolling step is performed. In the manufacturing method 4, the maximum working temperature between the quenching step and the final cold rolling step to the final size is set to 620 ° C., and the stress relief annealing is performed at the maximum intermediate annealing temperature of 520 ° C. , a parameter has a value between 4 × 10- ¹⁹ ~7 × 10- ¹⁸ hours, hot rolling, after hot rolling annealing, the use of a combination of time and temperature intermediate anneal Characteristic, A parameter is the hot rolling process and Per annealing step, the execution time of the process in terms of time, exp (-40000 /
T) is the sum of the segment parameters calculated by multiplying by T), and T in the above equation is the method for producing the strip-shaped zircaloy 4, which is the absolute temperature at the time of performing the above step.

[0007] Zircaloy 4 was processed according to the process sequence schematically illustrated in FIG. Zircaloy 4 was vacuum melted (block 60), forged (block 62), extruded (block 64), and then β-quenched (block 66). β-quenching was performed by induction heating a large diameter hollow cylinder for 4 minutes and then quenching with water. In producing channel strips,
The β-quenched material is hot rolled at 580 ° C. (block 68), recrystallized and annealed at a temperature of 580 ° C. for 2 hours (block 70), and subjected to two steps (40% of each step). Cold rolling (blocks 72 and 76) at 510 ° C
Intermediate stress relief annealing (block 7) for 2 hours
4) Then, a final heat treatment (block 78) was performed.
For the manufacture of the spacer, the β-quenched material is 58
Hot rolling (block 80) at 0 ° C, 2 at 580 ° C
Recrystallization annealing for a period of time (block 82), 510
Cold rolling (block 84) for 3 hours at ゜ C, 51
Stress relief annealing at 0 ° C for 3 hours (Block 8
6) Cold rolled (blocks 88, 92) in two steps (45% reduction in each step), stress relief annealing at 510 ° C. for 2 hours and 3 hours, respectively (blocks 90, 9)
4) and cold rolled (block 96) to final dimensions (44% reduction) and final heat treatment (block 98).

The content of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.

The current process sequence is schematically illustrated in FIG. Referring to FIG. 1, the strip-shaped Zircaloy 4 is manufactured through a vacuum melting step 10, a forging step 12, then a hot rolling step 14, and then a β-annealing step 16. β-annealing step 16 is 1015 ° C. to 113
A fluidized bed annealing treatment is performed at a temperature of 0 ° C. for 2 to 30 minutes, followed by quenching with water. To produce a channel strip of Zircaloy 4, the β-quenched material was hot rolled at 600 ° C. (block 20),
Anneal at 0 ° C. for 2 hours (22), cold-roll in two steps (blocks 24, 28) (40% in each step), 5
An intermediate stress relief anneal at 10 ° C for 2 hours (block 26) and a final recrystallization anneal at 650 ° C for about 3 hours (block 30). For the production of the Zircaloy 4 spacer strip, the β-quenched material is hot rolled at 600 ° C. (block 40).
Anneal at 600 ° C for 2 hours (Block 4
2) Then, cold rolling is performed in one step (block 44) and (40)
%), Stress relief annealing at a temperature of 510 ° C. for 2 hours (block 46) and cold rolling in two steps (block 4).
8,52) (40% in each step), then 3% at 510 ° C
During the time, stress relief annealing (blocks 50, 54) and cold rolling (block 56) to final dimensions (44%)
Followed by a final recrystallization anneal (block 58) at a temperature of 650 ° C. for 3 hours. This process sequence resulted in a cumulative A-parameter value of 4 × 10 ^{−19 to} 7 × 10 ⁻¹⁸ hours.

Zircaloy 4 was processed according to the process sequence shown schematically in FIG. Zircaloy 4 was vacuum melted (block 60), forged (block 62), extruded (block 64), and then β-quenched (block 66). β-quenching was performed by induction heating a large diameter hollow cylinder for 4 minutes and then quenching with water. In producing channel strips,
The β-quenched material is hot rolled at 580 ° C. (block 68), recrystallized and annealed at a temperature of 580 ° C. for 2 hours (block 70), and subjected to two steps (40% of each step). Cold rolling (blocks 72 and 76) at 510 ° C
Intermediate stress relief annealing (block 7) for 2 hours
4) Then, a final heat treatment (block 78) was performed.
For the manufacture of the spacer, the β-quenched material is 58
Hot rolling (block 80) at 0 ° C, 2 at 580 ° C
Recrystallization annealing for a period of time (block 82), 510
Cold rolling for 3 hours at ゜ C (block 84) and cold rolling in two steps (45% reduction in each step) (block 8)
8,92), and for 2 hours and 3 hours, respectively, at 510 ° C.
Stress relief annealing (blocks 90 and 94) and cold rolling (block 96) to final dimensions (44% reduction);
A final heat treatment (block 98) was performed.

The test for heterogeneous corrosion was carried out in a stationary autoclave at 500 ° C. for one day. The test for general corrosion by steam was carried out at a temperature of 460 ° C. for an exposure time of 3 to 88 days. These results are shown in FIG. The sign “+” indicates channel strip data, and the sign “□” indicates spacer data.

By using the process sequence shown in FIG. 2 and controlling the final recrystallization annealing process, the maximum resistance to general corrosion (400 ° C., FIG. 3A) and the maximum resistance to non-uniform corrosion (500 ΔC, FIG. 3B) was obtained. FIG. 3 shows that the cumulative A parameter is 4 × 10
^In the case of ^{−19 to} 7 × 10 ⁻¹⁸ hours, the maximum resistance to general corrosion (corrosion rate: mg / dm ² -days) and the maximum resistance to uneven corrosion (weight increase-mg / dm ² -days) were obtained. .

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an example of a processing order.

FIG. 2 is a schematic block diagram showing another example of a processing order.

FIGS. 3A and 3B are graphs showing corrosion test results at 400 ° C. and 500 ° C., respectively.

Continued on the front page (51) Int.Cl. ⁶ Identification FI C22F 1/00 683 C22F 1/00 684Z 684 685Z 685 686Z 686 691B 691 691C 694B 694 G21C 3/06 N (72) Inventor John Paul Foster United States of America Pennsylvania Courtesy of Monroeville, London 200 Delhi Court 200 (56) Reference JP-A-61-170552 (JP, A) JP-A-61-163254 (JP, A) JP-A-64-73060 (JP, A) JP-A 61-170 210166 (JP, A) Journal of Nuclear Materials, Vol. 173, no. 2, pp. 164-178 (1990) (58) Field surveyed (Int. Cl. ⁶ , DB name) C22F 1/18 G21C 3/07

Claims (4)

(57) [Claims] 1. Zircaloy 4 material is vacuum-melted, forged, hot-deformed, β-annealed, quenched, hot-rolled and post-hot-rolled, and then cold-finished to final dimensions. A method for producing a strip-shaped zircaloy 4 in which deformation is performed by at least two cold rolling steps including rolling, wherein intermediate annealing is performed between the cold rolling steps, and final annealing is performed after the final cold rolling step is performed. In the above, the maximum working temperature between the quenching step and the final cold rolling step to the final dimensions is set to 620 ° C., stress relief annealing is performed at the maximum intermediate annealing temperature of 520 ° C., and the A parameter is 4 × 10- ¹⁹
A value between the to 7-× 10- ¹⁸ hours, hot rolling, after hot rolling annealing, characterized by using a combination of time and temperature of the intermediate anneal, A parameter, hot For each of the rolling step and each annealing step, it is the sum of segment parameters calculated by multiplying the execution time of the step in time and exp (-40000 / T), and T in the above equation is A method for producing a strip-shaped Zircaloy 4, which is an absolute temperature at the time of implementation. 2. The hot rolling step and the post-hot rolling annealing step are performed at 560 to 620 ° C., and the intermediate annealing step is performed at 400 to 620 ° C.
The method for producing a strip-shaped zircaloy 4 according to claim 1, wherein the final annealing step performed at 520 ° C and after the final cold rolling step is performed at a temperature of 560 to 710 ° C, respectively. 3. The implementation time of the annealing step after the hot rolling step and the hot rolling step is 1.5 to 3 hours, the execution time of the final annealing step is 1.5 to 15 hours, 3. The method for producing a strip-shaped zircaloy 4 according to claim 2, wherein the time of the final annealing step performed after the cold rolling step is 1 to 5 hours. 4. The method of claim 1, wherein the β-annealing step comprises:
3. The method for producing a strip-shaped zircaloy 4 according to claim 2, wherein the method is performed at a temperature of 0 ° C. for 2 to 30 minutes.